1. Field
One or more embodiments relate to positive active materials and positive electrodes and lithium batteries including the positive active materials.
2. Description of the Related Art
Lithium secondary batteries have recently drawn attention as a power source for small portable electronic devices. They use an organic electrolytic solution, and thus, have a discharge voltage that is twice or more greater than that of conventional batteries using an alkali aqueous solution, and accordingly, have high energy density.
Lithium secondary batteries generate electric energy due to oxidation and reduction reactions occurring when lithium ions are intercalated into/deintercalated from a positive electrode and a negative electrode, each including an active material that enables intercalation and deintercalation of lithium ions, with an organic electrolytic solution or a polymer electrolytic solution interposed between the positive electrode and the negative electrode.
As a positive active material of a lithium secondary battery, LiCoO2 has been widely used. However, LiCoO2 is prepared at high manufacturing costs and it is difficult to have a stable supply thereof. Thus, as an alternative, a positive active material prepared in a composite with Ni or Mn has been developed.
As for a nickel-based composite oxide, a capacity per unit volume may be increased by increasing the amount of Ni or increasing a mass density of a positive active material. However, there is still a need to develop a positive active material with an improved packing density and good thermal stability and capacity.